Hello Rod,

> We ask a registrant to renew a domain name for 2 years.  
> During the course
> of the registration period the registrant decides to change 
> registrars or
> resellers. Is the registrant then in breach of a contract with us?

That would depend on your contract with the registrant.  Do you receive
payment up front?
Do you have a termination clause in your contract?  A company may decide to
bill a registrant on a monthly basis for 2 years, but if the contract is
terminated the registrant may be liable for the full amount.  See mobile
phone contracts.

Regardless, if the registrant chooses a new provider, then it will sign up
to whatever the registration agreement is with that new provider.

Regards,
bruce